Any server you run should have a regular full image backup done for disaster
When you first start a server, you shuld make a full drive image of all system
drives before releasing it to the public.
When you do scheduled upgrades of the OS or App Servers, you should make a
full drive image of all syste drives before releasing it to the public.
Backup the sites on a regular schedule as well, but that does not need to be a
drive image and can just be a standard backup to tape, remote drive, etc.
If you follow this, the worst that can happen is you have to replace the drive
and restore the system image(s), then restore the sites. A much better option
to completely rebuilding the systems from scratch and then explaining why the
sites are gone.